Atypical Neuropsychological Profile in a Boy with 22q11.2 Deletion Syndrome Keywords:

Including visual orienting functions into cerebral visual impairment screening: Reliability, variability, and ecological validity

BACKGROUND

Cerebral visual impairment (CVI) is a heterogeneous brain-based visual processing disorder in which basic visual orienting functions (VOF) and higher-order perception can be impaired.

AIMS

To evaluate (1) the test-retest reliability and variability of an eye tracking-based VOF paradigm, and related clinical characteristics, and (2) the relations between VOF (variability) and daily visual functioning and visuoperceptual dimensions.

METHODS AND PROCEDURES

Thirty-three children with CVI (Males=14; mean age=9 years 10 months) underwent eye tracking thrice, completed a visuoperceptual battery, and parents completed the Flemish CVI questionnaire. VOF reliability and variability of reaction time (RTF), fixation duration and accuracy were assessed with intraclass correlation coefficient (ICC), Bland-Altman plots, and coefficient of variation. Relations were analysed with linear mixed models.

OUTCOMES AND RESULTS

Highly salient visual stimuli had good RTF reliability (ICCs=0.75) and triggered less variable VOF. Intermediate and low salience stimuli had poor-to-moderate reliability and triggered more variable VOF. Younger performance age related to more VOF variability. Greater visual (dis)interest, clutter and distance viewing impairments, and a weaker visuoperceptual profile related to slower RTF.

CONCLUSIONS AND IMPLICATIONS

Highly salient stimuli reveal a child's 'optimal' visual performance, whereas intermediate and low salience stimuli uncover VOF variability, which is a key CVI hallmark to detect.

Quantifying visuoperceptual profiles of children with cerebral visual impairment

The aim was to develop a visuoperceptual profile schema reflecting visuoperceptual strengths and weaknesses, using neuropsychological tests. Secondly, this schema was used to quantify individual visuoperceptual profiles of children with and without cerebral visual impairment (CVI), and to identify differences in their profiles. Clinical records (2001-2018) of 630 children (386 males, 244 females; median age 77 months; interquartile range 63-98 months) suspected for CVI were reviewed. Neurological history, visuoperceptual results, ophthalmological, and neuroimaging data were retrieved. To develop the visuoperceptual schema, exploratory factor analyses (EFAs) were performed, followed by a Delphi study. In individual interviews, six experts were asked to "name the different visuoperceptual dimensions" and "what visuoperceptual dimensions are targeted by each of the 24 visuoperceptual subtests." To reach consensus, two questionnaire rounds (44 statements and 20 statements, respectively, five experts) followed. EFAs showed clinically uninterpretable results. The Delphi study revealed seven visuoperceptual dimensions; (1) visual discrimination and matching, (2) object or picture recognition, (3) visual spatial perception, (4) figure-ground perception, (5) motion perception, (6) visual short-term memory, and (7) scene perception. The most discriminating dimensions between CVI and no CVI were object/picture recognition (r = 0.56), visual spatial perception (r = 0.52), visual discrimination and matching (r = 0.47), and figure-ground perception (r = 0.39). Motion perception and visual short-term memory (both r = 0.22) were less discriminating. Two case studies illustrate how to apply the visuoperceptual schema to characterize dysfunction and intact functions. Visuoperceptual profiling can serve as a basis for individualized therapies in heterogeneous disorders.

Assessing age-related gray matter decline with voxel-based morphometry depends significantly on segmentation and normalization procedures

Healthy ageing coincides with a progressive decline of brain gray matter (GM) ultimately affecting the entire brain. For a long time, manual delineation-based volumetry within predefined regions of interest (ROI) has been the gold standard for assessing such degeneration. Voxel-Based Morphometry (VBM) offers an automated alternative approach that, however, relies critically on the segmentation and spatial normalization of a large collection of images from different subjects. This can be achieved via different algorithms, with SPM5/SPM8, DARTEL of SPM8 and FSL tools (FAST, FNIRT) being three of the most frequently used. We complemented these voxel based measurements with a ROI based approach, whereby the ROIs are defined by transforms of an atlas (containing different tissue probability maps as well as predefined anatomic labels) to the individual subject images in order to obtain volumetric information at the level of the whole brain or within separate ROIs. Comparing GM decline between 21 young subjects (mean age 23) and 18 elderly (mean age 66) revealed that volumetric measurements differed significantly between methods. The unified segmentation/normalization of SPM5/SPM8 revealed the largest age-related differences and DARTEL the smallest, with FSL being more similar to the DARTEL approach. Method specific differences were substantial after segmentation and most pronounced for the cortical structures in close vicinity to major sulci and fissures. Our findings suggest that algorithms that provide only limited degrees of freedom for local deformations (such as the unified segmentation and normalization of SPM5/SPM8) tend to overestimate between-group differences in VBM results when compared to methods providing more flexible warping. This difference seems to be most pronounced if the anatomy of one of the groups deviates from custom templates, a finding that is of particular importance when results are compared across studies using different VBM methods.

The motor profile of primary school-age children with a 22q11.2 deletion syndrome (22q11.2DS) and an age- and IQ-matched control group

In the early publications on the 22q11.2 Deletion Syndrome (22q11.2DS) motor abnormalities have been frequently reported. However, systematic studies on the motor performance of children with the 22q11.2DS, and especially of school-age children, are scarce. In this study the motor performance of primary school-age children with a 22q11.2DS (n = 28) was compared with an age- and IQ-matched control group (n = 28) using the Movement Assessment Battery for Children (MABC), the Körperkoordinationstest für Kinder (KTK) and the Beery-Buctenica test of Visual-Motor Integration (Beery). Children with a 22q11.2DS scored significantly lower than the age- and IQ-matched control group on the subsection Manual Dexterity (MABC) and the Visual Perception and Motor Coordination subtests of the Beery. When investigating the correlations between Intelligence quotient (IQ) and motor performance, a specific profile was found in the 22q11.2DS group when compared with the age- and IQ-matched control group. Because an IQ-matched control group was adopted, the deficits in visual-perceptual and visuomotor integration skills cannot fully be attributed to a general developmental delay and thus may be specific for the 22q11.2DS. Future studies that investigate the specificity of the visual-perceptual problems - both on the behavioral and brain level (functional Magnetic Resonance Imaging [fMRI] and Diffusion Tensor Imaging [DTI]) - are necessary to answer this question. Nonetheless, the importance of incorporating motor functioning into the study of the neuropsychological profile of children with a 22q11.2DS has to be stressed.

Visual perception in preterm children: what are we currently measuring?

Over the past two decades, cerebral visual impairment has been recognized as a principal deficit in preterm children, and in particular those with cerebral palsy. We review the current knowledge of visual processing deficits in these children, and provide an overview of the tools for assessing cerebral visual impairment. Commercially available instruments are usually directed at evaluating visuospatial skills rather than detecting object recognition difficulties. Particularly in children aged 3 years or younger and in children with multiple handicaps, cerebral visual impairment is difficult to diagnose. This difficulty may be attributable to limitations specific to the instrument, such as a test that is inappropriate for age, or to child-specific limitations such as motor impairment or speech delay. We therefore include an overview of relevant neuroimaging findings reported in these children, focusing on the most recent imaging modalities. Novel techniques such as diffusion tensor imaging may provide sensitive markers of cerebral visual impairment in situations where clinical diagnosis is difficult, and such approaches may allow for early intervention.

Scientific institutions and effective governance: a case study of Chinese stem cell research

In terms of stem cell research, China appears both as a "powerhouse" armed with state-of-the-art facilities, internationally trained personnel and permissive regulation and as a "bit player," with its capability for conducting high quality research still in question. The gap between China's assiduous endeavors and the observed outcome is due to a number of factors. Based on interviews with 48 key stakeholders active in Chinese stem cell research, this article examines how the structure of scientific institutions has affected effective governance in China. It is demonstrated that despite China's recent efforts to attract highly competent researchers and to launch new regulatory initiatives, the effects of these attempts have been diminished by an absence of middle-layer positions within research teams and by the uncoordinated administrative structures among regulatory bodies.

Cerebral Visual Impairment: which perceptive visual dysfunctions can be expected in children with brain damage? A systematic review

The current definition of Cerebral Visual Impairment (CVI) includes all visual dysfunctions caused by damage to, or malfunctioning of, the retrochiasmatic visual pathways in the absence of damage to the anterior visual pathways or any major ocular disease. CVI is diagnosed by exclusion and the existence of many different causes and symptoms make it an overall non-categorized group. To date, no discrimination is made within CVI based on types of perceptive visual dysfunctions. The aim of this review was to outline which perceptive visual dysfunctions are to be expected based on a number of etiologies of brain damage and brain development disorders with their onset in the pre-, peri- or postnatal period. For each period two etiologies were chosen as the main characteristic brain damage. For each etiology a main search was performed. The selection of the articles was based on the following criteria: age, etiology, imaging, central pathology and perceptive visual function test. The perceptive visual functions included for this review were object recognition, face recognition, visual memory, orientation, visual spatial perception, motion perception and simultaneous perception. Our search resulted in 11 key articles. A diversity of research history is performed for the selected etiologies and their relation to perceptive visual dysfunctions. Periventricular Leukomalacia (PVL) was most studied, whereas the main tested perceptive visual function was visual spatial perception. As a conclusion, the present status of research in the field of CVI does not allow to correlate between etiology, location and perceptive visual dysfunctions in children with brain damage or a brain development disorder. A limiting factor could be the small number of objective tests performed in children experiencing problems in visual processing. Based on recent insights in central visual information processing, we recommend an alternative approach for the definition of CVI that is based on functional visual processing, rather than anatomical landmarks. This could be of benefit in daily practice to diagnose CVI.

The organization of scientists and its relation to scientific productivity: Perceptions of Chinese stem cell researchers

Chinese government funding of R&D ranks third in the world. Yet China ranks only 17th in terms of scientific productivity per unit of investment. The author recently conducted fieldwork on the team structure of 22 Chinese stem cell research groups. Interview data suggest that although Chinese research groups closely resemble their international counter-parts in many respects, there are also significant differences which are perceived by interviewees to affect levels of scientific productivity. One characteristic of Chinese research teams is a common deficiency in middle-layer positions. This shortage of experienced professionals is perceived by scientists participating in this study to have led to two consequences. First, inexperienced student researchers often form the backbone of scientific teams in China, which leads to frequent interruptions of research and extended laboratory training. Second, research teams consist of a relatively small number of personnel. These structural features are seen to create excessive social boundaries, which impede the exchange of information and further worsens the segmentation of resources. This article engages the question of the extent to which interviewees' local 'embedded' understandings of these difficulties may make a productive contribution to the analysis of the structural, and infra-structural, organization of Chinese professional bioscience teams.

Assessment of cerebral visual impairment with the L94 visual perceptual battery: clinical value and correlation with MRI findings

In this article we describe visual perceptual abilities of a clinical population, referred for visual problems to our multidisciplinary team and assessed with the five computer tasks from the L94 visual perceptual battery. Clinical and neuroimaging findings were correlated with the findings on this task battery. Seventy children (35 males, 35 females) constituted our cohort. Age ranged from 4 to 20 years (mean 7y [SD 3y]). Forty children were born before 37 weeks gestational age. Thirty-six children had cerebral palsy (CP), of whom 24 had spastic diplegia, five had spastic hemiplegia, and four had spastic quadriplegia. Three children had ataxic CP. Perceptual visual impairment (PVI) was established in comparison to the performance age obtained on non-verbal intelligence subtests, instead of chronological age. Our results suggest that children with a history of preterm birth and a clinical CP picture are most at risk for a specific PVI. Correlations among other clinical variables did not define a clinical subgroup more at risk. Children with periventricular leucomalacia were almost equally represented in both PVI and non-PVI groups. Normal magnetic resonance imaging did not exclude the presence of PVI. In these children, however, we found another impairment profile, more in favour of dorsal stream impairment.